**Core Concept**
α-helices are a type of secondary structure in proteins, characterized by a spiral or helical arrangement of amino acid residues. This structure is stabilized by hydrogen bonds between the carbonyl oxygen of one residue and the amide hydrogen of another, four residues away. α-helices are a fundamental component of protein structure, playing a crucial role in maintaining the overall conformation and function of proteins.

**Why the Correct Answer is Right**
Long stretches of left-handed α-helices do not occur in proteins. In fact, left-handed α-helices are extremely rare in nature, and most proteins exhibit right-handed α-helices. This is due to the steric constraints imposed by the amino acid side chains, which favor a right-handed arrangement of the helix. The right-handed α-helix is also more thermodynamically stable than its left-handed counterpart. The hydrogen bonds in an α-helix are indeed aligned in the same direction, and this structure does have a net dipole moment, which is a characteristic feature of α-helices.

**Why Each Wrong Option is Incorrect**
**Option A:** α-helices are indeed one of the most important secondary structures in proteins, playing a crucial role in maintaining the overall conformation and function of proteins.
**Option B:** α-helices do have a net dipole moment, which arises from the alignment of the hydrogen bonds and the asymmetry of the peptide bond.
**Option C:** The hydrogen bonds in an α-helix are indeed aligned in the same direction, which contributes to the stability of the structure.

**Clinical Pearl / High-Yield Fact**
α-helices are a fundamental component of protein structure, and their stability is crucial for maintaining the overall conformation and function of proteins. Understanding the properties of α-helices is essential for understanding protein structure and function, which is critical for understanding various biological processes and diseases.

**✓ Correct Answer: D. Long stretches of left handed α-helices occur in proteins**